Pneumatic operating mechanism for a circuit interrupter with piston device having an opening piston and a closing piston

ABSTRACT

A circuit interrupter has a movable contact structure which is piston actuated. The operating piston rod has an opening piston and a closing piston secured thereto, so that upon entrance of high-pressure gas on one side of the opening piston, the opening piston will move to the open position carrying with it the movable contact structure. The closing piston, secured to the piston rod, has high-pressure gas acting on one side thereof at all times. A shock absorber structure may be used, and if used is also fixedly secured to the movable operating piston rod for the movable contact structure. Upon exhausting the high-pressure gas from the one face of the opening piston, the closing pressure, constantly acting upon one side of the closing piston, will effect a closing operation of the contact structure.

United States Patent [72] Inventors WilliamH.F'scher Pittsburgh;

Wayne S. Aspey, Monroeville. both of, Pa. [21] Appl. No. 762,479 [22]Filed Sept. 25, 1968 [45] Patented [73] Assignee June 29, 1971Westinghouse Electric Corporation Pittsburgh, Pa.

[$4] PNEUMATIC OPERATING MECHANISM FOR A CIRCUIT INTERRUPTER WITH PISTONDEVICE HAVING AN OPENING PISTON AND A CLOSING CLOSED POSITION HIGHPRESSURE Primary Examiner- Robert S. Macon v AttorneysA. T. Stratton,Clement L. McI-Iale and Willard R.

Crout ABSTRACT: A circuit interrupter has a movable contact structurewhich is piston actuated. The operating piston rod has an opening pistonand a closing piston secured thereto, so that upon entrance ofhigh-pressure gas on one side of the opening piston, the opening pistonwill move to the open position carrying with it the movable contactstructure. The closing piston, secured to the piston rod, hashigh-pressure gas acting on one side thereof at all times. A shockabsorber structure may be used, and if used is also fixedly secured tothe movable operating piston rod for the movable contact structure.

Upon exhausting the high-pressure gas from the one face of the openingpiston, the closing pressure, constantly acting upon one side of theclosing piston, will effect a closing operation of the contactstructure.

MAINTENCE JACK LOW PRESSURE HIGH PRESSURE- PATENTEU JUN29|97| 3.590.189

sum 2 pr 4 V LOW PRESSURE PRESSURE SF LOW \\PRESSURE PATENTEU JUN29 :97:

SHEU 3 UF 4 LOW PRESSURE HIGH PRESSURE PATENTEU M29 I971 SHEET [1F 4MAINTENCE JACK CLOSED POSITION LOW PRESSURE FIG .4

HIGH PRESSURE HIGH PRESSURE CROSS-REFERENCE TO RELATED APPLICATIONSReference may be had to U.S. Pat. application filed Dec. I0, 1968, Ser.No. 782,63l by William H. Fischer and Wayne S. Aspey.

BACKGROUND OF THE INVENTION As well known by those skilled in the art,in modern circuitinterrupting structures it is necessary to effectquick-opening and quick-closing operations. The industry trend has beentoward shorter opening cycles, such as, for example, two cycles ofalternating current. This is necessary to quickly diminish the amount ofenergy generated during the arcing period, and also, for application toreclosing circuit breakers, to prevent a loss of synchronism ofconnected electrical equipment.

It is, therefore, necessary to provide an operating mechanism for themovable contact structure of a circuit interrupter, which isquick-acting, reliable, adaptable for multiple-reclosing operations inthe event that the fault is only temporary in nature.

In addition, it is desirable to cushion the movable parts near theextremities of their opening and closing operations. For this purpose,shock absorbers of some kind have generally been employed.

It has been customary heretofore to provide a piston structuremechanically connected to the movable contact, so that the interruptercan be opened or closed upon the application of high-pressure gas.However, such structures have been lacking in speed of operation, andhave not been readily adaptable for reclosing circuit-interrupterarrangements.

SUMMARY OF THE INVENTION In accordance with a preferred embodiment ofthe present invention, there is provided an operating piston rodconnected to the movable contact structure of a circuit interrupter,which operating piston rod has both an opening piston and a closingpiston secured thereto. The arrangement is such that high-pressure gasconstantly acts on one face of the closing piston; and the openingpiston, being of larger cross-sectional area, has, for opening periods,high-pressure gas acting on one side thereof, with an exhausting of suchhigh-pressure gas during the closing operations.

Also fixedly secured to the operating piston rod, connected to themovable contact structure, is a shock absorber piston, which acts tocompress gas near the ends of the opening and closing operations, withthrottling being provided to bring the rapidly moving contact parts to acushioned stop.

It is, accordingly, one object of the present invention to provide aquick-opening and quick-closingpneumaticoperating mechanism for themoving-contact structure of a circuit interrupter.

Another object of the present invention is to provide a quick-openingand quick-closing operating mechanism for a circuit interrupter, whichhas provision for cushioning the movable parts near the ends of boththe'opening and closing strokes.

Still a further object of the present invention is the provision of animproved operating mechanism for the movable-contact structure of acircuit interrupter, which is readily accessible for maintenanceoperations, and, additionally, is readily accessible for regulating thevarious parts without dismantling the entire structure.

Still a further object of the present invention is the provision of animproved operating mechanism for the movable contact of a circuitinterrupter, which provides relatively constant opening and closingmovements regardless of variations in the operating high-pressure gas.

Further objects and advantages will readily become apparent upon readingthe following specification taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an end elevational view of athree-phase circuit interrupter embodying the principles of the presentinvention;

FIG. 2 is an enlarged cross-sectional view taken through theinterrupting assemblage of the circuit interrupter of FIG. 2 with thecontacts in the closed position;

FIG. 3 is an enlarged longitudinal partly sectional view taken throughthe movable contact structure of the circuit interrupter with thecontacts shown in the open position;

FIG. 4 is an enlarged vertical sectional view taken through the improvedpneumatic operating mechanism of the present invention, the severalparts being illustrated in the closed-circuit position; and

FIG. 5 is an enlarged sectional view taken through the pressureregulator.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, andmore particularly to FIG. 1 thereof, the reference numeral 1 generallydesignates a threephase circuit interrupter. The three-phase circuitinterrupter I of FIG. 1 comprises a plurality of spaced phase-unitsmechanically interconnected to a single ground potential operator.

With reference to FIGS. I and 2, it will be observed that, generally,the circuit-interrupting structure 1 is of generally U- shape. Extendingupwardly from a stationary supporting frame structure 4! is anarc-extinguishing assemblage, generally designated by the referencenumeral 6 (FIG. 2), and comprising one or more pairs of movable-contactstructures 7, which are separated and engaged, or closed in ahigh-pressure atmosphere 8.

Extending upwardly from the other side of the circuitbreaker structure 1is a terminal-bushing structure 10 (FIG. 1), which comprises ahigh-voltage conducting rod extending through a gaseous SF environment.Preferably, the gas is sulfur-hexaflouride (SF gas, which is usedbecause of its high dielectric strength properties. It is also used inthe arc extinguishing operation to interrupt the are under pressure.

The movable-contact structure 7 in each of the arc-extinguishingassemblages 6 is actuated by an operating piston rod 14, more clearlyshown in FIGS. 3 and 4 of the drawings. This operating rod 14 has anopening piston 15 and a closing piston 16 fixedly secured thereto. Inaddition, the operating-rod piston structure 14 has a shock-absorbingpiston 18 also secured thereto to cushion the movable contact parts ofthe circuit breaker near the ends of its high-speed opening and closingmovements.

It will be noted that the opening piston 15 moves within an operatingcylinder 20 of relatively large diameter, whereas the closing piston 16moves within an operating cylinder 21 of relatively small diameter.Additionally, it will be observed that the upper face 16a of the closingpiston 16 has high-pressure gas acting thereon at all times.High-pressure gas is admitted, at times, to the lower face 15a of theopening piston 15, as viewed in FIG. 4, during the opening operation,and is exhausted therefrom during the closing operation, such controlbeing obtained by the use of a three-way control valve, generallydesignated by the reference numeral 23, and mechanically controlled byan operating valve rod 15 (FIG. 2) extending generally vertically.

U.S. Pat. application filed Nov. I8, 1968 Ser. No. 776,510 by William H.Fischer and Wayne S. Aspey more clearly illustrates the internal detailsof the ground-potential operator (not shown), but for the purpose ofunderstanding the present I therethrough during a breaker-openingoperation. FIG. 3 shows the movable-contact structure 29in the fullyopen-circuit position, high-pressure gas existing in the region 31, anddownstream valves 33 being closed to prevent a continuing exhaustingflow-of gas through the separable movable contact structure 7. Thisfeature of the equipment is set forth in more detail, and claimed in US.Pat. application filed Sept. 16,

1968 Ser. No. 759,992, and assigned to the assignee of the presentinvention.

The operating mechanism 27 of the present invention has been found toprovide very good operational life, and hasmet the two-cycle dutyrequirements imposed thereon. As mentioned hereinbefore, generally, themain elements are the large opening piston 15, the relatively smallclosing piston 16, and the shock-absorbing piston 18. Additionally, themain valve 23 controls the opening and closing operations. As anadditional feature, there is provided a flow regulator 35 and a handjack 37, which will effect slow opening and closing contact operationsfor maintenance purposes.

An opening operation begins when the valve-control rod 25 is moveddownwardly, for example, threequarters of an inch. This moves thethree-way valve 23 from its closed to its open position, therebypermitting high-pressure SF, gas to flow into the large piston area adriving the opening piston 15 upwardly very' rapidly.

A closing operation begins when the valve-control rod is drivenupwardly, for example, three-quarters of an inch. This causes the valve25 to move to the breakenclosed position, and the high-pressure gas inthe large piston area 15a below the opening piston 15, is dumped, orexhausted to the low pressure. The top of the closing piston 16 hashigh-pressure gas acting on it at all times. The circuit interrupter lcloses with a force equal to the pressure times the closing-piston area16a.

To cushion the ends of the opening and closing high-speed operations,there is provided an SF, shock absorber 39, which is operated bytrapping SF, gas, compressing it and building up a back pressure force,and forcing such gas through holes in the cylinder portion 41 of theshock absorber 39. Bolts 43 are used to adjust the flow through thecylinder holes 41a. Check valves 45, 46 are used at either end to allowfree flow of the gas in one direction, and blocking the flow of such gasin the other direction.

Preferably, a linearly movable pressure-sensitive flow regulator, orbaffle (FIG. 5) gives constant opening and closing travel regardless ofthe operating pressure. During operating conditions, the pressure in thehigh-pressure source can vary over a considerable pressure range, for.example, from 180 psi. to 300 p.s.i. This high pressure acts in theoperating cylinder chamber 22 (FIG. 5) to move the baffle piston 35 tothe right under high-pressure conditions, as viewed in FIG. 5 to aposition as shown partially blocking off the flow of high pressure tothe opening piston 15, thereby compensating for such a high-pressurecondition. The reverse happens when the pressure of the high-pressuresource drops. It has been found by experimentation that adequate speedcontrol can be obtained without it, but if finer speed control isrequired, it is desireable to use it.

There is to be noted that with the construction of the improvedoperating mechanism 27, the shock absorber 39 can be adjusted withoutremoving the gas within the breaker, and also the lowpressure gas volumeis kept to a minimum.

The movable contact-operating rod 14 is connected to a generallyladder-shaped operating rod-structure 48 (FIG. 3), which effects openingand closing movements of the one or more movable contacts 29 within thearc-extinguishing assemblages 6, and, additionally, operates thedownstream valves 33 pneumatically connected to the interior of contactstructures 7. Generally the manner of arc interruption is such as toexhaust'high-pressure gas through the interior of the separable contacts7 themselves during the opening operation. When the operation iscompleted, the arc having been extinguished, the downstream valves 33are closed by the mechanical connection to the aforesaid ladder-shapedstructure 48.

-Sulfur-hexafluoride (SP6) gas atthe pressures being used (220 psi.normal) will begin to condense at 50 F. and below. Drains 34 (FIG. 4)are provided to remove this liquid from the mechanism 27. In FIG. 4 thepiston rod 14 has a hollow center 14a. The liquid collects on the piston16 and drains by gravity into the hollow shaft 14 through radial holes34. It drains out of shaft 14 at the bottom again through radial holes34. It drains out of shaft 14 at the bottom again through radial holes36 into intermediate sump 14b, which is connected to the high-pressuresource through pipe 24, where heat is provided and the liquid is againvaporized.

In place of the SP gas described for use in the shock absorber 39, ahydraulic shock absorber could be substituted, if desired.

Although there has been illustrated and described specific structure, itis to be clearly understood that the same was merely for the purpose ofillustration, and that changes and modifications may readily be madetherein by those skilled in the art without departing from the spiritand scope of the invention.

We claim:

I. An operating mechanism for a circuit interrupter including, incombination:

a. separable contact structure including a movable contact forestablishing an arc;

b. a piston device for actuating said movable contact including aclosing piston and a separate opening piston both secured to a pistonrod;

0. said piston rod being mechanically connected to the movable contact;and,

d. the cross-sectional area of the opening piston being larger than thecross-sectional area of the closing piston.

2. The combination according to claim 1, wherein highpressure gasconstantly acts on the closing face of the closing piston, andhigh-pressure gas is alternately admitted and exhausted from the openingface of the opening piston.

3. The combination according to claim 1, wherein a shock absorber pistonis also fixedly secured to the said piston rod to cushion the openingand closing operations of the contact structure.

4. The combination of claim 2, wherein a three-way opening control valvecontrols the admission and exhausting of highpressure gas to saidopening face of the opening piston.

5. The combination of claim 3, wherein the shock absorber pistonreciprocates within a perforated shock absorberoperating cylinder.

6. The combination according to claim 1, wherein the piston rod isextended externally of the circuit interrupter and is adaptable foroperation by a hand jack for maintenance purposes.

7. The combination according to claim 5, wherein regulating screws areexposed and control the perforations of the shock absorber-operatingcylinder thereby rendering them'accessible for adjustment.

8. The combination according to claim 3, wherein check valves areprovided at the ends of the operating cylinder for the shock absorber.

9. The combination according to claim I, wherein a pressure-sensitiveflow regulator is disposed between the opening piston and the valvecontrolling the flow thereto.

10. The combination of claim 3, wherein high-pressure gas constantlyacts on both sides of the shock absorber piston.

II. The combination of claim 5, wherein high-pressure gas constantlyacts on both sides of the shock absorber piston.

12. A compressed-gas operating mechanism for a circuit interruptercomprising, in combination:

a. means defining a low-pressure chamber having at least a portion of astepped operating cylinder projecting therewithin;

b. means defining a high-pressure chamber and disposed contiguously ofsaid low-pressure chamber and having a shock-absorbing cylinder disposedat least partially therein;

sorbing cylinder is perforated.

14. The combination of claim 12, wherein the shock-absorbing cylinderhas check valves disposed at opposite ends thereof.

15. The combination of claim 12, wherein high-pressure gas constantlyacts on one side of the closing piston and high-pressure gas isalternately admitted and exhausted from one face of the opening piston.

1. An operating mechanism for a circuit interrupter including, incombination: a. separable contact structure including a movable contactfor establishing an arc; b. a piston device for actuating said movablecontact including a closing piston and a separate opening piston bothsecured to a piston rod; c. said piston rod being mechanically connectedto the movable contact; and, d. the cross-sectional area of the openingpiston being larger than the cross-sectional area of the closing piston.2. The combination according to claim 1, wherein high-pressure gasconstantly acts on the closing face of the closing piston, andhigh-pressure gas is alternately admitted and exhausted from the openingface of the opening piston.
 3. The combination according to claim 1,wherein a shock absorber piston is also fixedly secured to the saidpiston rod to cushion the opening and closing operations of the contactstructure.
 4. The combination of claim 2, wherein a three-way openingcontrol valve controls the admission and exhausting of high-pressure gasto said opening face of the opening piston.
 5. The combination of claim3, wherein the shock absorber piston reciprocates within a perforatedshock absorber-operating cylinder.
 6. The combination according to claim1, wherein the piston rod is extended externally of the circuitinterrupter and is adaPtable for operation by a hand jack formaintenance purposes.
 7. The combination according to claim 5, whereinregulating screws are exposed and control the perforations of the shockabsorber-operating cylinder thereby rendering them accessible foradjustment.
 8. The combination according to claim 3, wherein checkvalves are provided at the ends of the operating cylinder for the shockabsorber.
 9. The combination according to claim 1, wherein apressure-sensitive flow regulator is disposed between the opening pistonand the valve controlling the flow thereto.
 10. The combination of claim3, wherein high-pressure gas constantly acts on both sides of the shockabsorber piston.
 11. The combination of claim 5, wherein high-pressuregas constantly acts on both sides of the shock absorber piston.
 12. Acompressed-gas operating mechanism for a circuit interrupter comprising,in combination: a. means defining a low-pressure chamber having at leasta portion of a stepped operating cylinder projecting therewithin; b.means defining a high-pressure chamber and disposed contiguously of saidlow-pressure chamber and having a shock-absorbing cylinder disposed atleast partially therein; c. a piston rod having a closing piston ofrelatively small diameter and a separate opening piston of relativelylarge diameter and a shock absorber piston all secured to and movablewith the piston rod; d. separable contact means including a movablecontact for establishing arcing; and, e. the piston rod beingmechanically connected to the movable contact.
 13. The combination ofclaim 12, wherein the shock-absorbing cylinder is perforated.
 14. Thecombination of claim 12, wherein the shock-absorbing cylinder has checkvalves disposed at opposite ends thereof.
 15. The combination of claim12, wherein high-pressure gas constantly acts on one side of the closingpiston and high-pressure gas is alternately admitted and exhausted fromone face of the opening piston.